to come to our aid. Either that, or we would have to let them
pass through without resisting them."

"So that they could fall on France? But that would be treachery!" said
Arthur, indignantly. "I have heard of that treaty of neutrality. We
are safeguarded from attack, but we are forbidden to allow the troops
of a country that is at war to pass through our territory. If it was
the French who talked of invading us to reach Germany, I should say
that we must fight them."

"Yes, you're right, Arthur," said Paul. "I think we should make any
sacrifice to keep faith. But be sure that it will be a terrible
sacrifice, if we must make it."

"Look there!" whispered Arthur, suddenly. "Someone started up just now
from behind the bushes. A man--and he is running away from us!"

"After him!" cried Paul. "It looks--yes, it is the man I spoke of!"

They ran as hard as they could, shouting as they went, in the hope that
someone might intercept the fugitive. But he had too good a start, and
in a few moments he had distanced them by climbing a rail fence and
disappearing into a thicket that came down to the edge of a field.

"No use!" said Paul, disgustedly. "He got away from us. But I don't
suppose it would have done us any good to catch him. We couldn't have
done anything--hello!"

He ended with an exclamation of surprise, and stooped over. They were
at the foot of the fence the flying figure had climbed a moment before.

"What is it, Paul?" asked Arthur, eagerly.

"This!" said Paul. He held up a small black pocket-book, and from it
he took a package of papers, wrapped in oil silk. "I struck against it
with my foot! I wonder if that man who was running could have dropped
it?"

It was almost dark by this time; too dark, at any rate, for them to be
able to see the papers. But then Arthur remembered the pocket
flashlight he carried and produced it, switching on the light.

"Let's have a look," he said.

They unwrapped the oil silk covering. And, at the first sight of what
was within it, they gasped. They were holding in their hands a
complete sketch of the fort of Boncelles, the most important of the
works defending Liege to the southwest. Before they could examine it
more fully there was a shout from the fence. The spy had missed his
papers. They saw him for a moment. But now it was their turn to run.

CHAPTER II

THE MARKED PLANS

The fierce shouting of the man as he called on them to stop